05/07/2012 11:35 am ET Updated May 07, 2012

Health Care Costs Have Older, Wealthier Americans 'Terrified,' Survey Shows

Health care costs have even the wealthy worried.

According to a new survey commissioned by Nationwide Financial and conducted by Harris Interactive, 46 percent of people 55 or older who have assets of at least $250,000 and plan to retire by 2020 say they are "terrified" that health care costs will foul up their retirement plans and 30 percent of those already retired reported the same anxiety. A smaller proportion of soon-to-be-retired Americans, 18 percent, is "fearful" of bankruptcy because of health care costs as are 6 percent of retired people, according to the survey.

These older Americans have good reason to worry, especially since the survey reveals they have an inaccurate picture of what their health care costs will be once they retire. Respondents on average predicted health care would cost them $5,621 a year out of pocket, but expenses could be almost twice that, according to Nationwide Financial. Of well-off people planning to retire by 2020, 43 percent say they don't even know what their medical expenses will be in retirement.

“Americans -- even those who have diligently saved for their golden years -- are not prepared for the reality of health care costs in retirement and don’t really understand how Medicare works,” said John Carter, president of Nationwide Financial Distributors. Harris Interactive conducted the online survey of 1,250 older Americans for Nationwide in January.

Medicare doesn't cover residential care in nursing homes and other forms of long-term care. Survey respondents underestimate how much they'll have to pay out of pocket for other expenses, the poll shows. People planning for retirement also often don't realize they will have to pay Medicare premiums out of their Social Security benefits, USA Today reports. Individuals with incomes of $85,000 pay higher premiums for Medicare coverage of doctor visits and prescription drugs than those who make less money.